Processing particle-containing samples

ABSTRACT

A microfluidic device includes an input port for inputting a particle-containing liquidic samples into the device, a retention member, and a pressure actuator. The retention member is in communication with the input port and is configured to spatially separate particles of the particle-containing liquidic sample from a first portion of the liquid of the particle containing fluidic sample. The pressure actuator recombines at least some of the separated particles with a subset of the first portion of the liquid separated from the particles. The device can also include a lysing chamber that receives the particles and liquid from the retention member. The lysing chamber thermally lyses the particles to release contents thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of, and claims priority under 35U.S.C. §120 to U.S. patent application Ser. No. 12/702,648, filed Feb.9, 2010, which is a continuation of U.S. patent application Ser. No.10/567,002, filed Jan. 31, 2006 (now U.S. Pat. No. 7,731,906), which isthe U.S. National Phase under 35 U.S.C. §371 of InternationalApplication No. PCT/US2004/025181, filed Aug. 2, 2004, which claimspriority under 35 U.S.C. §119 to U.S. Provisional Patent ApplicationNos. 60/491,269, filed Jul. 31, 2003, 60/551,785, filed Mar. 11, 2004,and 60/553,553, filed Mar. 17, 2004, which applications are incorporatedherein by reference in their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present application relates to microfluidic devices and methods foranalyzing biological samples, such as bacteria-containing samples.

2. Description of the Related Art

Microfluidic devices include devices with features having dimensions onthe order of nanometers to 100 s of microns that cooperate to performvarious desired functions. In particular, microfluidic devices performmaterial analysis and manipulation functions, such as performingchemical or physical analyses.

One type of microfluidic device allows the manipulation of discreteamounts of materials, such as samples and reagents, in addition to or asan alternative to continuous, flowing streams of material. Actuators canmove discrete amounts of materials within the microfluidic devices.

SUMMARY OF THE INVENTION

One aspect of the present invention relates to a microfluidic deviceconfigured to prepare an enriched particle-containing sample.

In some embodiments, the microfluidic device includes: an input port forreceiving a particle-containing liquidic sample, a retention member incommunication with the input port and configured to spatially separateparticles of the particle-containing liquidic sample from a firstportion of the liquid of the particle-containing fluidic sample, and apressure actuator configured to recombine at least some of the separatedparticles with a subset of the first portion of the liquid separatedfrom the particles.

In some embodiments, a microfluidic device includes an enrichmentregion, including: a retention member configured so that liquid of aparticle-containing liquid sample received therein exits the enrichmentregion along an exit path including a first surface of the retentionmember and particles of the particle-containing liquid sample areretained by the retention member; and a pressure actuator configured tointroduce fluid into the enrichment region along an entry path includingthe first surface of the retention member.

In some embodiments, a device for concentrating particles of aparticle-containing fluid includes: a substantially planar substrateincluding a microfluidic network and a mechanically actuated vacuumgenerator integral with the substrate, the vacuum generator including anexpandable chamber in fluidic communication with the microfluidicnetwork.

In some embodiments, a device for concentrating particles of aparticle-containing fluid includes: a first substrate and a secondsubstrate. The first and second substrates define between them at leasta portion of a microfluidic network and a chamber. The microfluidicnetwork includes a first end and a second end. The first end isconfigured to receive a sample including a particle-containing fluid.The second end of the microfluidic network is in fluidic communicationwith the chamber. The device also includes a manually actuated memberoperatively associated with the chamber and configured, upon actuation,to increase a volume thereof, so that a pressure within the chamberdecreases drawing fluid toward the second end of the microfluidicnetwork.

In some embodiments, a device for concentrating particles of aparticle-containing fluid includes a first substrate and a secondsubstrate. The first and second substrates define between themselves atleast a portion of a microfluidic network. The microfluidic networkincludes a filter configured to allow passage of fluid and to obstructpassage of particles that have a minimum dimension greater than apredetermined value with a source of vacuum in fluidic communicationwith the filter.

In some embodiments, a microfluidic device includes a microfluidicnetwork, including: an input port for receiving a particle-containingfluidic sample (PCFS), a filter configured to retain particles of thePCFS while allowing passage of fluid of the PCFS, and a vacuum generatorconfigurable to be in gaseous communication with the filter. Themicrofluidic device is configured to: subject a PCFS to a first pressureto expel a first amount of fluid of the PCFS through the filter whileretaining particles of the PCFS and subject the retained particles to asecond, reduced pressure to withdraw a second, smaller amount of fluidthrough the filter to prepare an enriched particle-containing fluidicsample.

In some embodiments, a microfluidic device includes a retention memberconfigured to retain particles of the particle-containing fluid whileallowing passage of fluid of the particle-containing fluid and a chamberconfigured to receive fluid that has passed through the retentionmember. The chamber is configured such that fluid passing thereinthrough the retention member increases a pressure within the chamber.

Another aspect of the invention relates to a method for enriching aparticle-containing fluidic sample.

In some embodiments, a method includes inputting a particle-containingliquidic sample into a microliquidic device including a retention memberhaving a first surface, spatially separating a first portion of theliquid of the liquidic sample from particles of the liquidic sample bypassing the first portion of the liquid through at least the firstsurface of the retention member and recombining the retained particleswith a subset of the first portion of the liquid.

In some embodiments, a method enriching a sample includes introducing aparticle-containing fluidic sample to a microfluidic network, applying apressure to the fluidic sample to expel a first amount of the fluid ofthe fluidic sample through a filter configured to retain particles ofthe fluidic sample within the microfluidic network, and subjectingretained particles of the fluidic sample to a reduced pressure to causea second, smaller amount of fluid to enter the microfluidic networkthrough the filter and entrain the particles to form an enrichedparticle-containing sample.

In some embodiments, a method for concentrating particles of aparticle-containing fluid, includes introducing a particle-containingfluid to a microfluidic network of a microfluidic device. Themicrofluidic network includes a filter having a first side. The filteris configured to (a) allow passage of the fluid through the first sideand (b) obstruct passage of the particles through the first side. Thedevice also includes a vacuum generator configured to generate a vacuumwithin at least a portion of the microfluidic network. A first side ofthe filter is contacted with the particle-containing fluid whereupon atleast a first portion of the fluid passes through the filter to thesecond side of the filter and the particles remain on the first side ofthe filter. The vacuum generator is actuated to withdraw a subset of thefirst portion of fluid back through the first side of the filter.

In some embodiments, a method for enriching a particle-containingfluidic sample includes contacting a particle-containing fluidic samplewith a filter so that a first portion of the fluid of the PCFS passesthrough the filter and particles of the PCFS are retained by the filter,the fluid passing through the filter entering a chamber and increasing apressure therein and allowing a second, smaller portion of the fluid topass back through the filter and recombine with the particles retainedby the filter.

In some embodiments, a method for enriching a particle-containingfluidic sample includes introducing a particle-containing fluidic sample(PCFS) to a sample processing device including a microfluidic networkand a chamber separated from the microfluidic network by a retentionmember, introducing a first amount of the fluid of the PCFS to thechamber by passing the fluid through the retention member. The fluidpassing into the chamber increases a pressure therein. Particles of thePCFS are retained by the retention member. A second, smaller amount offluid is allowed to exit the chamber by passing back through theretention member, the fluid that exits the chamber re-combining withparticles retained by the retention member.

In some embodiments, a method for enriching a particle-containingfluidic sample includes driving fluid of the particle-containing fluidicsample through a retention member configured to retain particles of theparticle-containing fluidic sample. Fluid passing through the retentionmember enters a closed chamber and increases a pressure therein. Apathway is provided for fluid present in the chamber to exit therefrom.The pathway includes the retention member such that fluid exiting thechamber passes back through the retention member and recombines withparticles retained by the retention member.

In one embodiment of the present invention, a microfluidic deviceincludes one or more thermally actuated elements. A preferred thermallyactuated element includes a single source of heat configured to bothincrease a pressure with a chamber and increase a temperature of a massof a thermally response substance (TRS) in gaseous communication withthe chamber. At the increased temperature, the increased pressure withinthe chamber is sufficient to move the TRS. For example, the pressure maybe sufficient to move the TRS from a side channel of a microfluidicnetwork into a main channel of the network thereby obstructing passageof material in the main channel. Advantageously, use of a single sourceof heat reduces the amount of power required to actuate such thermallyactuated elements. Thermally actuated elements actuated via a singlesource of heat reduce the complexity of controller electronics andsoftware as compared to thermally actuated elements actuated via two ormore sources of heat.

In another embodiment of the present invention, a microfluidic deviceincludes a typically planar substrate including one or more thermallyactuated elements. A first side of the substrate includes elements of amicrofluidic network, such as a channel and a side channel thatintersects the channel. A second, opposed side of the substrate includesa chamber connected to the channel via the side channel. An amount ofTRS is disposed in the side channel intermediate the channel and thechamber. Increasing a gas pressure within the chamber may move the TRSinto the channel thereby sealing the channel. Advantageously, thechamber and various other elements of the microfluidic network arelocated on opposite sides of the substrate thereby allowing moreefficient use of the space available on the first side of the substrate.

Another aspect of the invention relates to a microfluidic deviceincluding a first substrate including first and second opposed surfaces.The second surface defines, at least in part, a chamber. The firstsurface defines, at least in part, a channel configured to accommodatemicrofluidic samples and a side channel intersecting the channel andconnecting the chamber with the channel. An amount of a thermallyresponsive substance (TRS) is disposed in the side channel intermediatethe chamber and the channel. A second substrate can be mated with thefirst surface of the first substrate. A third substrate can be matedwith the second surface of the first substrate.

Another aspect of the present invention relates to a microfluidic devicefor processing a cell-containing sample to release intracellularmaterial from cells of the sample.

In some embodiments, a microfluidic device includes a lysing zone, aheat source disposed to heat cell-containing sample present within thelysing zone to release intracellular material from cells of the sample,and first and second valves each having a loading state and a lysingstate. When the first and second valves are in the loading state, acell-containing sample may be introduced to the lysing zone, and, whenthe first and second valves are in the closed state, the cell-containingsample present in the lysing zone may be heated for a time sufficient tolyse cells of the cell-containing sample without substantialevaporation, e.g., with less than 25% loss, less than 20% loss, or lessthan 15% loss, of a liquid component of the sample.

The volume of the lysing chamber can be 25 microliters or less, 20microliters or less, 5 microliters or less e.g. 2 microliters or less.

The valves can include an amount of temperature responsive substance,e.g., wax, to prevent evaporation of the liquid component.

At least one of the valves, e.g., a downstream valve, can be configuredas a gate. Prior to loading the sample into the lysing region, the gateis configured in the closed state and includes a mass of temperatureresponsive substance that obstructs the downstream passage of thematerial. Upon actuation, at least a portion of the temperatureresponsive substance passes downstream, thereby opening the gate.

In some embodiments, a microfluidic device for amplifyingpolynucleotides of a sample includes a reaction zone, a heat sourcedisposed to polynucleotides present within the lysing zone to denaturethe polynucleotides, and first and second valves each having a loadingstate and a reaction state. When the first and second valves are in theloading state, a polynucleotide-containing sample may be introduced tothe reaction zone, and, when the first and second valves are in theclosed state, the polynucleotide-containing sample present in thereaction zone may be heated for a time sufficient to subject thepolynucleotides to at least 3 cycles of thermal denaturation andannealing without substantial evaporation of a liquid component of thesample, e.g., without evaporation of more than 10%, e.g., more than 5%,of the liquid component.

One aspect of the invention relates to a microfluidic system including amicrofluidic device including a lysing zone. The lysing zone has avolume of less than 25 microliters, e.g., about 20 microliters or less.The lysing zone typically includes an inlet channel and an outletchannel. The microfluidic device also includes one or more valves and/orgates. In a first state, the valves and/or gates are configured to allowa sample to be introduced to the lysing zone. In a second state, thevalves and/or gates are closed to limit or prevent liquid or gas fromescaping from the lysing zone even when aqueous contents of the lysingzone are heated to, e.g., about 98° for a time of, e.g., about 3minutes. In a third state, the valves and/or gates are configured toallow sample to exit the lysing zone.

Typically, at least one mass of temperature responsive substance (TRS)is used to inhibit material from exiting the lysing zone in the secondstate. In some embodiments, in the third state, the TRS may passdownstream along the same channel as material exiting the lysing zone.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of an exemplary microfluidic device;

FIG. 2 is a side view of a first embodiment of a microfluidic device;

FIG. 3 is a top view of the microfluidic device of FIG. 2;

FIG. 4 is a top view of a second embodiment of a microfluidic device;

FIG. 5 is a top perspective view of the microfluidic device of FIG. 4;

FIG. 6 a is a top view of a third embodiment of a microfluidic device;

FIG. 6 b is a side view of the microfluidic device of FIG. 6 a;

FIGS. 6 c and 6 d illustrate the introduction of sample material to themicrofluidic device of FIG. 6 a, more sample material having beenintroduced in FIG. 6 d than in FIG. 6 c.

FIG. 7 is a top view of a fourth embodiment of a microfluidic device;

FIG. 8 is a top view of a fifth embodiment of a microfluidic device;

FIG. 9 a is a top view of a sixth embodiment of a microfluidic device;

FIG. 9 b is a close-up view of a portion of the microfluidic device ofFIG. 9 a, an amount of sample having been added;

FIG. 9 c is a close-up view of a portion of the microfluidic device ofFIG. 9 b, an amount of sample having been added and a microdroplet ofthe added sample moved downstream;

FIG. 10 is a top view of a device for alternatively obstructing andpermitting passage of material within a microfabricated channel;

FIG. 11 is a cross section looking down a side channel of the device ofFIG. 10;

FIG. 12 shows the device of FIG. 10 with a heat source positioned toactuate the device; and

FIG. 13 is a top view of a seventh embodiment of a microfluidic device,the device having an integral mechanical vacuum generator.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to microfluidic systems and devices andmethods for manipulating and processing materials, such as samples andreagents. Microfluidic devices generally include a substrate thatdefines one or more microfluidic networks, each including one or morechannels, process modules, and actuators. Samples and reagents aremanipulated within the microfluidic network(s). The modules andactuators of the networks are typically thermally actuated. For example,a process module can include a reaction chamber that is heated by a heatsource. An actuator may include a chamber that is heated to generate apressure or a vacuum to move material within the netowork.

Typical samples include particle-containing fluidic samples. The fluidcomponent of the particle-containing fluidic sample may include a gasand/or, a liquid, e.g., a buffer, water, organic solvents, saliva,urine, serum, blood, or combination thereof. In any case, the fluidtypically entrains the particles such that the particles tend to movewith the fluid.

The particles of the particle-containing fluidic sample generallyinclude cells, such as bacterial cells or cells of an animal, such as ahuman. The particles may include intracellular material released fromsuch cells. For example, the microfluidic systems may detect (uponoptional amplification) polynucleotides, e.g., DNA, released from cells.In some embodiments, the microfluidic system processes DNA released frombacteria cells to determine the presence, absence, and/or abundance ofthe bacteria, e.g., bacteria associated with Group B streptococcal (GBS)disease. Other particles that may be analyzed include tissue, viruses,spores, fungi, and other microorganisms and material released fromwithin such particles.

Microfluidic Systems and Devices

Referring to FIG. 1, an exemplary microfluidic network 110 of amicrofluidic device has a sample input module 150 and reagent inputmodule 152 to allow sample and reagent materials, respectively, to beinput to network 110. Generally, one or both of input modules 150, 152are configured to allow automatic material input using a computercontrolled laboratory robot. Network 110 may also include output portsconfigured to allow withdrawal or output of processed sample from or bymicrofluidic network 110.

Within a microfluidic network, material generally travels from upstreamlocations to downstream locations. For example, sample materialgenerally travels downstream from an input port to other locationswithin the microfluidic network. In some cases, however, the directionof flow may be reversed.

Locations of network 110 downstream from the input module typicallyinclude process modules 156, 158, 160, 166 and 162 for processing thesample and reagent materials. Within these process modules, a sample issubjected to various physical and chemical process steps. For example,enrichment module 156 receives a particle-containing fluid and preparesa fluid sample having a relatively higher concentration of particles.Lysing module 158 releases material from particles of an enrichedsample, e.g., the module releases intracellular material from cells.Lysing can be accomplished using, for example, thermal, ultrasonic,mechanical, or electrical techniques. Exemplary lysing modules arediscussed in U.S. provisional application No. 60/491,269, filed Jul. 31,2003, and U.S. patent application Ser. No. 10/014,519, filed Dec. 14,2001, which applications are incorporated herein by reference.

DNA clean-up module 160 readies polynucleotides, e.g., DNA, releasedfrom the particles for detection. For example, DNA clean-up module 160can be configured to prepare a DNA sample for amplification bypolymerase chain reaction. Sample DNA processed by clean-up module 160moves downstream within network 110. An exemplary DNA clean-up module isdiscussed in U.S. provisional application No. 60/567,174, filed May 3,2004, which application is incorporated herein by reference.

Mixing module 166 mixes DNA received from module 160 with reagents fromreagent input module 152. Typical reagents include PCR primers,reagents, and controls. Exemplary reagents are used in the amplificationand detection of GBS bacteria, such as reagents disclosed in U.S. patentapplication Ser. No. 10/102,513, filed Mar. 20, 2002, which applicationis incorporated herein. Reagent materials may be loaded during useand/or stored within the microfluidic device during manufacturing.Certain reagent materials can be lyophilized to extend their storagelife. Liquid reagents can be stored within a chamber, e.g., a metalizedpouch, for mixing with dried reagents. In some embodiments, amicrodroplet having a selected volume is prepared from fluid releasedfrom the chamber within the microfluidic device. The microdroplet iscombined with dried reagents to prepare a known concentration of reagentmaterials.

PCR-Detection Module 162 receives DNA released from sample particles andreagents and detects minute quantities of DNA therein. In general,process module 162 is configured to amplify the DNA such as by PCR.Detection is typically spectroscopic, as by fluorescence. In someembodiments, the presence and/or abundance of DNA is detectedelectrochemically.

PCR-Detection module 162 typically includes more than oneamplification/detection chamber. One chamber generally receives anddetects (with optional amplification) DNA released from sampleparticles. Another chamber typically receives and detects (with optionalamplification) control DNA, which may be used to indicate whethernetwork 110 is functioning properly. Other modules of network 110, e.g.,reagent and mixing modules 152, 166 are configured to accommodate thepresence of more than one amplification/detection chamber.

Various modules of microfluidic network 110 are connected, such as bychannels 164, to allow materials to be moved from one location toanother within the network 110. Actuators 168, 170, 172 associated withthe microfluidic device provide a motive force, such as an increased gaspressure and/or a decreased gas pressure to move the sample and reagentmaterial along the channels and between modules. Some gas actuators movematerials by reducing a pressure in a downstream portion of amicrofluidic network relative to a pressure in an upstream portion ofthe microfluidic network. The resulting pressure differential moves thematerial downstream toward the region of reduced pressure. As usedherein, the term vacuum does not require the total absence of gas orother material. Rather, a vacuum means a region having at least areduced gas pressure as compared to another region of the microfluidicdevice, e.g., a partial vacuum. The volume of channels and chambersassociated with a vacuum actuator is typically reduced by placing fluidcontrol elements, e.g., valves or gates, as near to the vacuum chamberof the actuator as is feasible.

First actuator 168 of network 110 moves material downstream fromenrichment module 156 to lysing module 158. Upon completion ofprocessing within lysing module 158, a second actuator 170 movesmaterial downstream to DNA clean-up module 160. Subsequently, actuator170 or an additional actuator moves cleaned-up DNA to mixing module 166,where the material mixes with a reagent moved by actuator 172. Finally,actuator 172, or another actuator, moves the mixed material toPCR-detection module 162.

Because, in some embodiments, each actuator is responsible for movingmaterials within only a subset of the modules of network 110, samplematerials can be controlled more precisely than if a single actuatorwere responsible for moving material throughout the entire device. Thevarious functional elements, of microfluidic network 110, including theactuators, are typically under computer control to allow automaticsample processing and analysis.

As used herein, the term microfluidic system includes not only amicrofluidic device defining a microfluidic network but also the heatsources to operate thermally actuated modules and actuators of themicrofluidic device. The heat sources can be integrated with themicrofluidic device or incorporated in another component of themicrofluidic system such as a receptacle that receives the microfluidicdevice during operation. The various functional elements, ofmicrofluidic network 110, including the heat sources, are typicallyunder computer control to allow automatic sample processing andanalysis. Systems and methods for computer control of microfluidicsystems are disclosed in U.S. patent application Ser. No. 09/819,105,filed Mar. 28, 2001, which application is incorporated herein byreference.

Actuators, enrichments modules, lysing modules, and other aspects ofmicrofluidic devices and systems are discussed below.

Microfluidic Devices Including a Vacuum Actuator

As discussed above, actuators can manipulate samples within microfluidicdevices by reducing a downstream pressure relative to an upstreampressure within the device. In some embodiments, such actuators are usedin combination with an enrichment module to prepare a sample having anenriched amount of particles. The enriched sample can be delivered to alysing chamber within the microfluidic device. Such devices arediscussed below.

Referring to FIGS. 2 and 3, a microfluidic device 50 includes asubstrate 47 including a first layer 71, a second layer 73, and a thirdlayer 75. The layers of substrate 47 define a microfluidic network 51.Network 51 includes channels, modules, and actuators such as, e.g.,those of microfluidic network 110 discussed above. At least somecomponents of network 51 are typically thermally actuated. Thus,substrate 47 may mate in use with a second substrate 76, which includesheat sources configured to be in thermal communication with thermallyactuated components of microfluidic network 51. Alternatively, the heatsources may be integral with substrate 47, e.g., substrates 47 and 76may be integral. Suitable heat sources for actuating thermally actuatedcomponents are discussed in copending U.S. application Ser. No.09/783,225, filed Feb. 14, 2001 and 60/491,539, filed Aug. 1, 2003,which applications are incorporated herein.

In the embodiment shown, network 51 includes an input port 54 by whichsample material may be introduced to network 51, an enrichment region 56connected to input port 54 by a channel 58, and a vacuum generator 52configured to manipulate material within the microfluidic network andconnected to enrichment region 56 by a channel 60. Port 54 may include afitting 55 to mate with a syringe or other input device and may alsoinclude a septum through which a needle or other cannulated sampleintroduction member may be inserted.

As indicated by a symbollic break 64, microfluidic network 51 mayinclude other modules or components, e.g., a reaction chamber, a lysingmodule for releasing material from cells or other biological particles,a DNA clean-up module, a reagent mixing chamber, output port, and thelike. These other modules or components are typically disposeddownstream of enrichment region 56. For example, a typical embodimentincludes a lysing chamber to receive an enriched particle sample fromenrichment region 56 and an amplification-detection chamber foramplifying and detecting DNA released from particles of the sample.

Vacuum generator 52 includes a gate 62, a chamber 66, a valve 68, and aport 70, which may be in gaseous communication with the ambientenvironment around device 50. Gate 62 is configured in a normally closedstate in which gate 62 obstructs passage of material, e.g., samplematerial and gas, between chamber 66 and upstream portions ofmicrofluidic network 51 such as enrichment region 56. In an open state,gate 62 allows such passage of material.

Valve 68 is configured in a normally open state in which valve 68 allowspassage of material, e.g., gas, along a channel 86 between chamber 66and port 70. In a closed state, valve 68 obstructs passage of materialbetween chamber 66 and port 70. Valve 68 typically includes a chamber 84and a mass of thermally responsive substance (TRS) 80. In the closedstate, the TRS obstructs passage of material whereas in the open state,the TRS is dispersed or withdrawn from the channel to allow passage ofmaterial therealong.

Whether for a gate or a valve, the obstructing mass of TRS can have avolume of 250 nl or less, 125 nl or less, 75 nl or less, 50 nl or less,25 nl or less, 10 nl or less, 2.5 nl or less, 1 nl or less, e.g., 750picoliters or less. In some embodiments of a gate or valve, some or allof the TRS passes downstream upon opening the gate or valve. Forexample, the TRS may pass downstream along the same channel as samplepreviously obstructed by the TRS. In some embodiments, the TRS melts andcoats walls of the channel downstream from the position occupied by theTRS in the closed state. The walls may be at least partially coated forseveral mm downstream. In some embodiments, the TRS disperses and passesdownstream as particles too small to obstruct the channel. Exemplarygates and valves including a mass of TRS are disclosed in U.S. Pat. No.6,575,188, issued Jun. 10, 2003, which patent is incorporated herein byreference.

Exemplary TRS resist movement at a first temperature and can morereadily be moved at a second, higher temperature. The first temperaturemay be about 25° C. or less and the second higher temperature may be atleast about 40° C. The second higher temperature may be a meltingtemperature or a glass transition temperature of the TRS. Suitablematerials include wax, a polymer, or other material having a meltingpoint (or glass transition temperature) of at least 50° C., e.g., of atleast 75° C. Preferred TRS materials have melting points (or glasstransition temperatures) of less than 200° C., e.g., less than 150° C.Typical TRS materials are hydrophobic but may be hydrophilic.

Raising a temperature within chamber 84 increases a pressure therein.When the temperature within chamber 84 is raised and the temperature ofTRS 80 is also raised, the pressure within chamber 84 moves TRS 80 intochannel 86 connecting port 70 and chamber 66 thereby obstructing thepassage of material, e.g., gas, along channel 86. Substrate 76 includesa heater 82 configured to be in thermal contact with both chamber 84 andTRS 80 when substrates 76 and substrate layer 71 are mated. Actuatingheater 82 raises both the temperature within chamber 84 and thetemperature of TRS 80 to the second temperature.

Gate 62 is typically a thermally actuated gate including a mass of TRS74. When substrate layer 71 and substrate 76 are mated, heater 78 andgate 62 are disposed in thermal contact. Actuating heater 78 raises thetemperature of TRS 74 to the second temperature.

Even when a pressure differential exists between chamber 66 and upstreamportions of network 51, the TRS 74, when at the first temperature,prevents the passage of material between chamber 66 and upstreamportions of network 51. When the temperature of TRS 74 is raised to thesecond temperature, such a pressure differential is typically sufficientto move and/or disperse TRS 74 allowing material, e.g., gas, to passinto chamber 66 from upstream portions of network 51.

When both gate 62 and valve 68 are in the closed state, chamber 66 isconfigured to maintain a pressure that is less than about 90%, less thanabout 80%, less than about 70%, less than about 60%, less than about50%, or less than about 35% of the pressure acting upon the oppositeside of valve 68. The pressure acting upon the opposite side of valve 68is typically the ambient pressure around device 50, e.g., about 1atmosphere. Generally, the reduced pressure within chamber 66 can bemaintained for at least 15 seconds, at least 30 seconds, at least 60seconds, at least 120 seconds, e.g., at least 300 seconds.

Valves and gates in accord with the present invention may have identicalstructures with the exception that, unless otherwise specified, a valveis normally configured in an open state and a gate is normallyconfigured in a closed state.

A method for preparing a vacuum within chamber 66 typically includes theat least partial evacuation of gas from chamber 66 and the sealing ofthe evacuated chamber to prevent material from re-entering the chamber.Evacuation is generally achieved by heating chamber 66. For example,when substrate layer 71 and substrate 76 are mated, chamber 66 is inthermal contact with a heat source 41 of substrate 76. Actuation of theheat source 41 raises the temperature of material present within chamber66. The material within the chamber may include, e.g., a gas and/orvaporizable material such as a liquid or a material that is capable ofsublimation at a temperature of between about 50° C. and about 200° C.

Vacuum generator 52 is typically used to manipulate materials withinnetwork 51 of device 50. In some embodiments, vacuum generatorcooperates with enrichment region 56 to prepare an enriched sample. Theenrichment region is now discussed in greater detail.

Enrichment region 56 includes a retention member 94, a valve 85, and adownstream gate 88. Retention member 94 generally includes a filter toselectively retain particles of a particle-containing sample as comparedto fluid (e.g. a liquid) of the particle-containing sample, such as toallow the passage of fluid but limit or prevent the passage of theparticles. Typically, retention member 94 allows the passage of fluidtherethrough but retains particles by size exclusion. For example,retention member 94 allows fluid to exit enrichment region 56 by passingthrough retention member 94 but retains particles within the enrichmentregion. Fluid that passes through retention member 94 enters a reservoir98 configured to contain such fluid.

In some embodiments, retention members are configured to retain, such asby size exclusion, bacteria, e.g., GBS from culture and clinicalsamples. An exemplary retention member is a polycarbonate track-etchfilter defining, e.g., 0.6 μm pores, such as is available from Poretics.

Enrichment region 56 may communicate with retention member 94 via a hole89, which may open to a cavity 91 defined at least in part by a surface97 of retention member 94. Cavity 91 allows the particle-containingsample to contact retention member 94 over a surface area that isgreater than a surface area of hole 89. Cavity 91 may be tapered asshown to facilitate entry of fluid and particles to and removal of fluidand particles from cavity 91. As an alternative to cavity 91, hole 89may communicate with a network of channels that distribute fluid over asurface 97 of retention member 94.

Reservoir 98 may be sealed, such as by a fluid impermeable membrane (notshown), to prevent fluid expelled through retention member 94 fromleaking into the surrounding environment. The sealed volume of thereservoir may be as great as or greater than the total internal volumeof enrichment chamber 56 and portions of network 51 downstream thereof.

A retention member support 96 helps retain retention member 94 inposition against internal pressure created by the introduction of sampleand the passage of fluid through retention member 94. Support 96 may bea grid fabricated as part of substrate layer 73.

Gate 88 has a normally closed state to obstruct passage of materialbetween enrichment region 56 and downstream portions of microfluidicnetwork 51. Gate 88 has an open state in which material may pass fromenrichment region 56 to downstream portions of network 51. Gate 88 maybe a thermally actuated gate including a mass of TRS 90 and actuated bya heat source 92 of substrate 76.

Valve 85 has a normally open state in which material may pass betweenupstream portions of microfluidic network 51 and enrichment region 56.Valve 85 has a closed state, which obstructs material from passingbetween enrichment region 56 and upstream regions of microfluidicnetwork 51. Valve 85 may be a thermally actuated valve including a massof TRS 85 and a chamber 87. Substrate 76 includes a heat source 93configured to actuate valve 85 as discussed for valve 68.

Enrichment region 56 of device 50 may be operated as follows. A particlecontaining fluid sample is introduced to network 51, e.g., via port 54,such as by using a syringe or other sample introduction device. Theamount of sample introduced may be at least, e.g., 250 microliters, atleast 500 microliters, or at least 1,000 microliters. The amount offluid, e.g., liquid, introduced may be, e.g., less than 10,000microliters, less than 5,000 microliters, or less than 2,500microliters. Enrichment region 56 is typically configured so that (withdownstream gate 88 closed) fluid entering device 50 must pass throughretention member 94 to exit the enrichment region. Theparticle-containing fluidic sample passes along channel 58 intoenrichment region 56.

Retention member 94 spatially separates at least some and preferablymost of the fluid of the received fluidic sample from particles of thereceived fluidic sample. For example, liquid of a fluidic sample maypass through or beyond at least surface 97 of retention member 94whereas retention member 94 retains particles of the fluidic sample,such as at surface 97 thereof. Fluid, e.g., liquid, that passes throughor beyond surface 97 exits enrichment region 56 and may pass intoreservoir 98. Fluid that has passed beyond surface 97 may be describedas having been expelled from the microfluidic network.

Retention member 94 retains particles of the fluid sample, such as bysize exclusion and/or by adsorption and/or absorption of the particles.Thus, once the fluidic sample has been introduced, reservoir 98 containsfluid of the sample whereas particles of the sample are retained withinenrichment region 56, such as at surface 97 of retention member 94.However, some of the fluid of the fluidic sample may remain within theenrichment region 56 (interior to surface 97) and in contact with theretained particles. This amount of fluid is typically less than about50%, less than about 25%, less than about 10%, less than about 5%, e.g.,less than about 2% relative to the total amount of fluid received byenrichment region 56. The total amount of fluid received by theenrichment region 56 is typically between about 1 and 10 ml.

Once a sufficient amount of sample has been introduced, valve 85 isactuated to the closed state thereby preventing passage of materialbetween enrichment region 56 and upstream portions of network 51, e.g.,port 54. Particles retained by the filter may be moved away from thefilter by causing fluid to pass into enrichment region through retentionmember 94 along a path that is substantially opposite to the pathfollowed by fluid of the fluidic sample in passing beyond surface 97 andinto reservoir 98.

In some embodiments, device 50 is configured such that a gas pressuredownstream of enrichment region 56, e.g., downstream of gate 88, is lessthan a gas pressure external to surface 97 of retention member 94. Whengate 88 is opened, the pressure differential causes some fluid, e.g.,fluid within reservoir 98, e.g., liquid of the particle-containingsample, to enter enrichment region 56, combine with retained particlestherein and move the particles away from the retention member 94. Avacuum may be used to obtain the pressure differential.

A vacuum may be prepared as follows. With valve 68 (of vacuum generator52) configured in the open state and at least one gate intermediatevacuum generator gate 52 and enrichment region 56 (e.g., gate 62)configured in the closed state, heat source 41 is actuated therebyraising a temperature of material within chamber 66. Gas present withinthe chamber expands and at least some of the expanded gas exits network51 via port 70. If a liquid is present within chamber 66, the liquid mayvaporize with at least some of the vapor also exiting via port 70.Similarly, the elevated temperature may sublimate a solid present withinchamber 66. Once the temperature within chamber 66 has been raised to agiven temperature for a given time, valve 68 is closed and thetemperature within chamber 66 is allowed to decrease.

Upon the reduction of temperature within chamber 66, the pressure, e.g.the total gas and vapor pressure therein, decreases and creates apressure differential between chamber 66 and enrichment region 56. Oncethe pressure differential has reached a sufficient level, chamber 66 andenrichment region 56 are brought into gaseous communication such as byactuating any closed gates (e.g., gate 62 and/or 90) along channel 60.With chamber 66 and enrichment region 56 in communication, a pressuredifferential is created between a pressure of gas above fluid inreservoir 98 and a pressure within enrichment region 56. The pressuredifferential draws a portion of the fluid present in reservoir 98through retention member 94 and into enrichment region 56. The fluidpreferably passes through retention member 94 in an opposite directionfrom the direction taken by fluid during expulsion through retentionmember 94. The direction of flow may be substantially orthogonal tolayer 73. The direction of flow may be substantially orthogonal to aplane defined by network 51.

The fluid entering enrichment region 56 combines with particles retainedby retention member 94 during sample introduction and forms an enrichedparticle-containing sample typically including a smaller volume fluid,e.g., liquid, than was introduced into network 51 and a substantialportion of the particles that were retained by retention member 94. Theamount of fluid that passes into, e.g., back into, enrichment region 56through retention member 94 is typically less than 50%, less than 10%,less than 2.5%, or less than 1% of the volume of fluid, e.g., liquid,introduced with the sample. For example the amount of fluid, e.g.,liquid, that passes into enrichment region 56 through retention member94 may be less than 50 microliters, less than 25 microliters, less than15 microliters, less than 10 microliters, or less than 5 microliters.The retention member 94 no longer retains the particles of the enrichedparticle-containing sample so that the enriched particle-containingsample moves away from the retention member.

It should be understood that at least a portion of the fluid expelledthrough retention member 94 and into reservoir 98 may be replaced withother fluid, such as fresh buffer or a different buffer. In this case,the fluid passing into enrichment region 56 through retention member 94includes at least some and perhaps substantially all of the other fluid.Thus, the fluid entering into the enrichment region 56 through retentionmember 94 is not limited to the fluid that was expelled upon introducingthe particle-containing sample.

In addition to preparing the enriched fluid, the pressure differentialis typically sufficient to also move the enriched fluid into adownstream portion of microfluidic network 51. However, the downstreammovement can be accomplished using another vacuum generator or a sourceof positive pressure source in addition to or as an alternative tovacuum generator 52.

Typically enrichment ratios, i.e., the volume concentration of particlesin the enriched fluid relative to the volume concentration of particlesin the introduced fluid, are at least 5, at least 10, at least 25, atleast 50 or at least 100. The enriched fluidic sample may be withdrawnfrom network 51 or subjected to further processing and or analysistherein.

Referring to FIGS. 4 and 5, a microfluidic device 200 receives a sample,e.g., a particle-containing sample, and enriches the sample to preparean enriched sample including a greater relative concentration of theparticles. In the embodiment shown, device 200 includes a microfluidicnetwork 201 including an input port 204, a channel 205 along whichsample material received via input port 204 may pass, a vent 206configured to allow gas accompanying the received sample material toexit network 201, and a channel 207 disposed downstream of vent 206. Anenrichment region 202 is located downstream of channel 207.

Input port 204 can include a fitting 232 (FIG. 5) configured to matewith a syringe or other input device. Vent 206 may include a gaspermeable hydrophobic membrane, e.g., a porous polytetrafluoroethylenemembrane available from W. L. Gore, Inc.

Channels 205 and 207 are separated by a valve 208, which generally has anormally open state configured to allow at least downstream passage ofmaterial from channel 205 to channel 207. Valve 208 can be actuated to aclosed state configured to obstruct passage of material betweenenrichment region 202 and portions of network 201 upstream of valve 208.Valves of device 200 may be configured as thermally actuated valvesdiscussed for device 50.

Enrichment region 202, which may be configured as enrichment region 56,receives sample material introduced via port 204 and prepares anenriched sample enriched in a desired particle. Enrichment region 202includes a retention member 94, a retention member support 236, whichmay be configured as support 96, and a reservoir 234, which may beconfigured as reservoir 98.

Network 201 also includes a channel 209 located downstream of enrichmentregion 202 to receive enriched sample material therefrom. Channel 209includes a gate 216 configured to selectively permit the downstreampassage of material between enrichment region 202 and portions ofnetwork 201 downstream of gate 216.

Gate 216 has a normally closed state which obstructs the passage ofmaterial, e.g., enriched sample and/or gas, between enrichment region202 and portions of network 201 downstream of gate 216. Gate 216 may beactuated to an open state in which material may pass between enrichmentregion 202 and downstream portions of network 201. Gates of device 200may be configured as thermally actuated gates discussed for device 50.

Gate 216 is connected to downstream portions of network 201 via achannel 219. In the embodiment shown, network 201 includes an outputport 210 a connected to channel 219 via a channel 220. Enriched samplematerial may be withdrawn manually or output automatically from port 210a by device 200. A gate 212 having a normally closed state selectivelyobstructs or permits passage of material between channel 220 and outputport 210 a.

Other downstream portions of network 201 are connected to channel 219via a channel 218. For example, an output port 210 b is connected tochannel 218 via a channel 224. Enriched sample material may be withdrawnmanually or output automatically from port 210 b by device 200. A gate222 having a normally closed state selectively obstructs or permitspassage of material between channel 218 and output port 210 b.

Device 200 can be configured to enrich a sample as follows. Gate 216 isconfigured in the closed state obstructing passage of material betweenenrichment region 202 and downstream portions of network 201. Valve 208is configured in the open state. An amount of sample material isintroduced to channel 205, such as by using a syringe configured to matewith fitting 232. The amount of sample introduced may be as describedfor device 50. The introduced sample material passes vent 206, whichallows gas to exit channel 205 but resists the exit of fluid andparticles of the sample material. Sample material passes downstream ofvent 206 and is received by enrichment region 202.

Retention member 94 allows fluid of the sample material to exitenrichment region 202 but retains particles, such as by allowing thepassage of fluid but limiting or preventing the passage of the particlesas described above. The fluid is expelled through retention member 94and into reservoir 234, which may be sealed as for reservoir 98.Particles of the sample are retained within enrichment region 202 asdescribed above.

Network 201 may be configured to manipulate, e.g., move, materialtherein by using pressure differentials therein. For example, thecreation of a relatively decreased pressure in a first portion of thenetwork relative to a pressure in a second portion of the network can beused to urge material from the second toward the first portions of thenetwork. The relatively decreased pressure can be created by a decreasein the absolute pressure in the first portion and/or an increase in theabsolute pressure in the second portion. In the embodiment shown, device200 includes a vacuum generator 215 configured to create a decreasedpressure at locations downstream of enrichment region 202 relative to apressure within enrichment region 202 and/or a pressure above fluidwithin reservoir 234. Device 200 can use the pressure differential tomove enriched sample material from enrichment region 202 to downstreamportions of network 201.

Vacuum generator 215 includes a chamber 214, a port 230, and a valve208. Chamber 214 communicates with channel 220 (and therefore channel209 and enrichment region 202 when gate 216 is in the open state) via achannel 218 and a channel 226. Chamber 214 communicates with port 230via a channel 228. Valve 208 permits selective obstruction of channel228 so that the passage of material, e.g., gas, between chamber 214 andport 230 may be obstructed. Port 230 and valve 208 may be configured andoperated as port 70 and valve 68 respectively.

Device 200 may be configured for creating a partial downstream vacuum asfollows. Gate 209 is configured in the closed state thereby preventingor at least limiting the passage of gas between enrichment region 202and chamber 214. If either of output ports 210 a, 210 b are present,gates 212, 222 are configured in the closed state, thereby preventing orat least limiting the passage of gas into or out of network 201 viaports 210 a, 210 b. Valve 208 is configured in the open state therebyallowing the passage of material, e.g., gas between chamber 214 and port230, which typically provides the only passage for gas to exit network201 from chamber 214. Gas present within chamber 214 is heated causingthe gas to expand. At least some of the expanded gas exits chamber 214(and therefore network 201) via port 210. When the gas has been expandedto a desired extent, valve 208 is closed and the remaining gas isallowed to cool causing a partial vacuum to form within chamber 214.

Device 200 may be configured to use a partial vacuum with chamber 214 toprepare an enriched sample as follows. A particle-containing fluidsample is introduced as described above so that retention member 94retains particles. Fluid is present within reservoir 234. The fluid mayinclude fluid expelled through retention member 94 and/or fresh oradditional fluid as described for device 50. The partial vacuum withinchamber 214 is prepared. Gate 216 is actuated, such as by heating a TRSthereof, thereby placing chamber 214 in communication with enrichmentregion 202 and creating a pressure differential between the pressure ofa gas above the fluid in reservoir 234 and chamber 214. The pressuredifferential operates as discussed for enrichment region 56 to withdrawan amount of fluid back through retention member 94 and back intoenrichment region 202 to prepare an enriched particle containing sample.The enriched sample may be prepared in the same amounts and with thesame properties as for device 50.

In addition to preparing the enriched fluid, the pressure differentialbetween chamber 214 and above fluid in reservoir 234 is typicallysufficient to also move the enriched fluid into a downstream portion ofmicrofluidic network 201. However, the downstream movement can beaccomplished using another vacuum generator or a source of positivepressure source in addition to or as an alternative to vacuum generator215. Gate 216 may be re-sealed thereby preventing the passage ofadditional material between enrichment region 202 and downstreamportions of network 201.

Vacuum generator 215 may be actuated a second time to move the enrichedsample again. For example, at least one of gates 212, 222 may beactuated to place ports 210 a, 210 b in communication with network 201.Gas within chamber 214 is heated creating a pressure increase thatdrives the enriched sample toward ports 210 a, 210 b. Alternatively,network 201 may contain additional modules, e.g., a lysing module, areagent mixing module, a reaction module, etc., for subjecting theenriched sample to further processing within network 201. Additionalvacuum generators or pressure generators may be added to effect furthermovement of the enriched and or processed sample within these modules.

Referring to FIGS. 6 a and 6 b, a microfluidic device 600 is configuredto receive an amount of a particle-containing fluidic sample and toprepare an enriched sample including a greater abundance of theparticles. The preparation of the enriched sample includes spatiallyseparating particles of the particle-containing sample from (at leastsome) fluid of the sample, e.g., liquid of the sample. Device 600 usespressure created during the spatial separation to recombine a subset ofthe fluid that was separated from the particles with the particles.These and other aspects of device 600 are discussed below.

Device 600 includes a microfluidic network 601 including an input port654, a sample enrichment region 602 connected to the sample port by achannel 605, a pressure actuator 607 located downstream of enrichmentregion 602 and connected thereto by a channel 609, and an output port611 in communication with channel 609.

Channel 605 includes a vent 606 configured to allow gas to exit channel605. Vent 606 may have features of vent 206 discussed above.

Channel 605, upstream of enrichment region 602, includes a valve 608 toselectively obstruct passage of material between input port 654 andenrichment region 602. Valve 608 may have features of valve 208 or othervalves (or gates) discussed herein. Valve 608 is preferably configuredto have a normally open state that allows material to pass along channel605.

As an alternative or in combination with valve 608, device 600 caninclude a 1-way valve configured to allow sample to enter channel 605and pass downstream but configured to limit or prevent material, e.g.,gas, from passing upstream from chamber 699 and exiting device 600 viaport 654. An exemplary valve is a duckbill valve available fromMinivalve International, Oldenzaal, The Netherlands. Such a valve can belocated at port 654, e.g., in combination with fitting 655, or disposedalong channel 605.

Channel 609, downstream of enrichment region 602, includes a gate 616 toselectively allow passage between enrichment region 602 and downstreamlocations of microfluidic network 601. Gate 616 may have features ofgate 216 or other gates (or valves) discussed herein. Gate 616 isgenerally configured to have a normally closed state that obstructspassage of material between enrichment region 602 and downstreamlocations of network 601.

Network 601 includes a passage 635 that connects output port 611 andchannel 609. The passage 635 includes a gate 637 to selectively obstructor allow passage between channel 609 and output port 611. Gate 637 mayhave features of gate 216 or other gates (or valves) discussed herein.Gate 637 is generally configured to have a normally closed state thatobstructs passage of material between channel 609 and output port 611.

Pressure actuator 607 includes a gate 639 to selectively allow passagebetween actuator 607 and channel 609. Gate 639 may have features of gate216 or other gates (or valves) discussed herein. Gate 639 is generallyconfigured to have a normally closed state that obstructs passage ofmaterial between actuator 607 and channel 609.

Enrichment region 602 includes a retention member 694 to spatiallyseparate particles of a particle-containing sample from fluid of theparticle-containing sample. Retention member 694 preferably allowsfluid, e.g., gas and/or liquid, to pass therethrough and into reservoir698. Retention member 694 typically retains particles within a cavity691 that is at least in part defined by a surface 697 of retentionmember 694. Enrichment region 602 may have features of enrichment region56 or other enrichment regions discussed herein. Retention member 694may have features of retention member 94 or other retention membersdiscussed herein. For example, retention member 694 may operate to allowthe passage of fluid but limit or prevent the passage of the particlesby size exclusion, binding, and/or adsorption.

Referring also to FIGS. 6 c and 6 d, reservoir 698 defines asubstantially gas impermeable chamber 699. Fluid that enters chamber699, such as by passing through retention member 694, decreases a freevolume thereof and increases a pressure therein. Thus, the pressurewithin chamber 699 is greater in FIG. 6 d than in 6 c because more fluidhas been introduced to the chamber 699. The force needed to overcome theintroduction of fluid to chamber 699 is provided during the introductionof sample to device 600.

Chamber 699 may include a valve, e.g., a pressure relief valve (notshown), configured so that each introduction of sample into device 600creates the same pressure within chamber 699. Exemplary pressure reliefvalves are umbrella valves available from Minivalve International. Apressure relief valve can be used in any pressure chamber of devicesherein. Typically, the relief valve opens when the pressure differentialbetween pressure within chamber 699 and pressure external to chamber 699exceeds about 0.5 psi, about 1 psi, about 2 psi, or about 3 psi. Largervolume chambers typically have valves that open at lower pressures thansmaller volume chambers.

Device 600 may be operated as follows. A particle-containing sample isintroduced to device 600, such as by using a sample introduction device,e.g., a syringe 696, mated with fitting 655 of input port 654. Withvalve 608 in the open state and gate 616 in the closed state, samplematerial passes along channel 605 into enrichment region 602. Pressurecreated by the sample introduction device drives fluid of the samplethrough retention member 694 and into chamber 699 of reservoir 698. Asdiscussed above, the entry of fluid into chamber 699 increases thepressure therein. Retention member 694 retains particles of the samplewithin cavity 691 of enrichment region 602.

Once a sufficient amount of sample material has been introduced, theenrichment region may be sealed to prevent pressure created withinchamber 699 from being vented or driving material out of enrichmentregion 602. For example, valve 608 may be actuated to the closed stateto prevent passage of material between input port 654 and enrichmentregion 602 along channel 605. With both valve 608 and gate 616 in theclosed state, device 600 maintains the pressure within chamber 699.

To prepare an enriched particle-containing fluidic sample, gate 616 isactuated to the open state thereby providing a passage for material toexit chamber 699. The relatively greater pressure within the chamberdrives fluid therein through retention member 694 and into cavity 691 ofenrichment region 602. Thus, the fluid passes through retention member694 in an opposite direction from the fluid that entered chamber 699through retention member 694.

Typically, only a subset of fluid that entered chamber 699 passes backthrough retention member 694. The amount of fluid, e.g., liquid, thatpasses into enrichment region 602 through retention member 694 istypically less than 50%, less than 10%, less than 2.5%, or less than 1%of the volume of fluid, e.g., liquid, introduced with the sample. Forexample the amount of fluid, e.g., liquid, that passes into enrichmentregion 602 through retention member 694 may be less than 50 microliters,less than 25 microliters, less than 15 microliters, less than 10microliters, or less than 5 microliters. Thus, device 600 prepares anenriched particle-containing sample including particles of theparticle-containing sample and a subset of the fluid that was originallyintroduced to device 600.

A volume of a downstream portion of network 601 may determine the volumeof fluid (e.g., the volume of the subset) that recombines with theparticles. Typically, the downstream portion is defined betweenenrichment region 602 and a downstream vent. For example, downstreamchannel 609 includes a vent 613, e.g., a gas-permeable hydrophobicmembrane, that allows gas to exit network 601 but substantially preventsliquid from exiting network 601. With gate 616 open, pressure withinchamber 699 drives the enriched sample along channel 605 toward the vent613. Gate 637 prevents material from exiting network 601 via port 611.Gate 639 prevents material from entering pressure actuator 607.

Upon the enriched sample material reaching vent 613, channel 609 isfilled with enriched sample material and the downstream passage ofadditional material from enrichment region 602 is limited or prevented.Thus, the downstream volume of channel 609 defines the volume of liquidthat may exit chamber 699 and recombine with particles to prepare theenriched sample material. Although the downstream passage of additionalmaterial is limited or prevented by vent 613, the pressure withinchamber 699 may be vented, e.g., by re-opening valve 608. Alternatively,or in combination, gate 616 (or a valve downstream of chamber 699, notshown) may be re-closed (or closed) to isolate chamber 699 from channel609.

Device 600 may include additional modules, such as one or more of thoseof system 110 of FIG. 1. Such modules are preferably configured tofurther process the enriched sample, such as by lysing cells thereof,removing polymerase chain reaction inhibitors, mixing the enrichedsample with reagent, and the like. For devices including such modules,passage 635 may connect with these modules rather than leading to outputport 611. In such embodiments, device 600 may be configured to drive aknown volume of the enriched sample material downstream toward theadditional modules. Alternatively, device 600 may be configured to expela known amount of the enriched sample material from the device via port611.

A known amount of enriched sample material may be driven downstream orexpelled as follows. With enriched sample material present in channel609, pressure actuator 607 is actuated to generate pressure therein. Forexample, actuator 607 may include a gas chamber in thermal communicationwith a heat source. The heat sources may be integral with device 600 orlocated in a separate substrate 671 as for device 50. In any event, heatfrom the heat source expands gas present in the chamber of actuator 607and generates pressure. To move the enriched sample, gates 637 and 639are opened allowing pressure within the actuator 607 to move theenriched sample. The volume of enriched sample is determined by thevolume of network 601 downstream of actuator 607 and upstream of vent613. Thus, device 600 may be configured to prepare and/or deliver anenriched sample having a known volume. The volume of a prepared and adelivered sample need not be the same.

Referring to FIG. 7, a microfluidic device 700 receives an amount of aparticle-containing fluidic sample and prepares an enriched sampleincluding a greater abundance of the particles. The preparation of theenriched sample includes spatially separating particles of theparticle-containing sample from fluid of the sample. Device 700 usespressure created during the spatial separation to manipulate sampleand/or reagent material, such as to move such materials about device700. These and other aspects of device 700 are discussed below.

Device 700 includes a microfluidic network 701 including an input port754, an enrichment region 756 in communication with input port 754 by achannel 702, and a reservoir 798 defining a chamber 799 to receive fluidfrom enrichment region 756.

Channel 702, upstream of enrichment region 756, includes a valve 708 toselectively obstruct passage of material between input port 754 andenrichment region 756. Valve 708 may have features of valve 208 or othervalves (or gates) discussed herein. Valve 708 has a normally open statethat allows material to pass along channel 702.

Enrichment region 756 includes a retention member 794 to spatiallyseparate particles of a particle-containing sample from fluid of theparticle-containing sample. Retention member 794 allows fluid, e.g., gasand/or liquid, to pass therethrough and into reservoir 798 whileretaining particles. Enrichment region 756 may have features ofenrichment region 56 or other enrichment regions discussed herein.Retention member 794 may have features of retention member 94 or otherretention members discussed herein.

Chamber 799 defines a first portion 791 and a second portion 793separated by a liquid barrier, e.g., an internal wall 789, configured toallow gas to pass between portions 791, 793 but to prevent liquid frompassing between these portions of chamber 799. A channel 711 extendsdownstream from first portion 791. A channel 723 extends downstream froman outlet 719 of second portion 793 and joins channel 711 at anintersection 713.

Channel 723 includes a gate 725 to selectively obstruct or allow passagebetween second portion 793 of chamber 799 and downstream portions ofchannel 723. Gate 725 may have features of gate 216 or other gates (orvalves) discussed herein. Gate 725 has a normally closed state thatobstructs passage. A vent 755 is in gaseous communication with channel723. A valve 757, having a normally open state, is configured toselectively allow or obstruct passage of gas between channel 723 andvent 755.

Channel 711 includes a gate 716 and a gate 759 to selectively obstructor allow passage between enrichment region 756 and downstream locationsof microfluidic network 701. Gates 716 and 759 may have features of gate216 or other gates (or valves) discussed herein. Gates 716 and 759 aretypically configured to have a normally closed state that obstructspassage of material between enrichment region 756 and downstreamlocations of network 701. Downstream locations of network 701 typicallyinclude lysing module 158, DNA clean-up module 160, detection module162, and reagent module 152.

Device 700 may be operated as follows. A particle-containing sample isintroduced, such as by using a sample introduction device, e.g., asyringe, mated with a fitting 755 of input port 754. With valve 708 inthe open state and gates 716,725 in the closed state, sample materialpasses along channel 702 into enrichment region 756. Pressure created bythe sample introduction device drives fluid of the sample throughretention member 794 and into first portion 791 of chamber 799 ofreservoir 798. Entry of fluid into first portion 791 of chamber 799increases the pressure within chamber 799. Retention member 794 retainsparticles of the sample within enrichment region 756.

Once a sufficient amount of sample material has been introduced, theenrichment region may be sealed to prevent pressure created withinchamber 799 from being vented or driving material out of enrichmentregion 756. For example, valve 708 may be actuated to the closed stateto prevent passage of material between input port 754 and enrichmentregion 756 along channel 702. With valve 708 and gates 716, 725 in theclosed state, device 700 maintains the pressure within chamber 799.

To prepare an enriched sample, gate 716 is actuated to the open statethereby providing a passage for material to exit chamber 799. Therelatively greater pressure within the chamber drives fluid thereinthrough retention member 794 and into enrichment region 756. Thus, thefluid preferably passes through retention member 794 in an oppositedirection from the fluid that entered chamber 799 through retentionmember 794.

Typically, only a subset of fluid that entered chamber 799 passes backthrough retention member 794. The amount of fluid, e.g., liquid, thatpasses into enrichment region 756 through retention member 794 istypically less than 50%, less than 10%, less than 2.5%, or less than 1%of the volume of fluid, e.g., liquid, introduced with the sample. Forexample the amount of fluid, e.g., liquid, that passes into enrichmentregion 756 through retention member 794 may be less than 50 microliters,less than 25 microliters, less than 15 microliters, less than 10microliters, or less than 5 microliters. Thus, device 700 prepares anenriched particle-containing sample including particles of theparticle-containing sample and a subset of the fluid that was originallyintroduced to device 700.

Typically, pressure within chamber 799 also drives the enrichedparticle-containing sample toward downstream portions of network 701. Insome embodiments, a volume of the enriched particle-containing sampledriven downstream is determined by a volume of a downstream portion ofnetwork 701. For example, with gates 725, 759 closed and upon actuatinggate 716, pressure within chamber 799 drives at least a portion of theenriched particle sample along channel 711 and into channel 723 beyondintersection 713. Enriched sample is driven along channel 723 until adownstream terminus of enriched sample reaches vent 755 inhibitingfurther movement of the sample. The volume of the enriched sample issubstantially determined by a volume of channel 723 intermediate vent755 and gate 759.

Once sample has filled channel 723, gate 716 may be re-closed or a valve(not shown) located along channel 711, may be actuated to obstructpassage of material between channel 723 and enrichment region 756. Then,gates 725 and 759 are actuated. Opening gate 725 places intersection 713between channels 711 and 723 in communication with second portion 793 ofchamber 799 via outlet 719. With gate 725 open, pressure within chamber799 drives material further downstream of intersection 713. For example,the pressure may drive material toward lysing module 158.

Chamber 799 of device 700 may include one or more additional outputports configured to allow pressure within chamber 799 to be used tomanipulate and/or move sample, reagent, or other materials elsewherewithin network 701. For example, outlet 717 communicates with channel733 which itself intersects with channel 709 upstream of lysing region158. A gate 735 selectively obstructs or allows passage of materialbetween outlet 717 and channel 733. A gate 737 selectively obstructs orallows passage of material between channels 709 and 733. Uponpreparation of a lysed sample, gates 735, 737 are opened whereuponpressure from chamber 799 moves the lysed sample downstream of lysingchamber 158.

Referring to FIG. 8, a microfluidic device 300 includes a sampleenrichment region 302, a port 304 for introducing sample material todevice 300, a port 306 for the output of processed sample material, achannel 308 connecting the enrichment region 302 and, and a valve 310for obstructing passage of material along channel 308 between enrichmentregion 302 and port 304.

In use, a given amount of sample material is introduced via port 304,which may be configured to mate with a standard syringe. The amount ofsample introduced depends upon the analysis and may be, e.g., at leastabout 0.25 ml, at least about 0.5 ml, at least about 1 ml, and, e.g.,less than about 5 ml, less than about 2.5 ml, or less than about 1.5 ml.

Sample material passes along channel 308 to enrichment region 302. Thefluid travels into the concentration region (including a circular filterwhose center is typically free and whose edge 309 is secured to thechip) and through the filter leaving the cells or other particles ofinterest behind at an internal surface of the filter. The waste fluid,may pool on top of the device, and can be discarded, assuming a thinmeniscus of liquid remains on the top of the filter to prevent dryingand to provide a reservoir from which to backflow. Once the cells aretrapped by the filter, the user actuates the valve 310, thus obstructingthe passage of material between port 304 and enrichment region 302. Thenthe tape is removed, and an external device, e.g., a pipette or syringe,is used to backflow some of the liquid of the sample back through thefilter to re-entrain the cells. Typically, less than 25%, less than 10%,less than 5%, less than 2.5%, or less than 1% of the fluid introducedwith the particles re-entrains the particles.

Microfluidic Device Including a Thermally Actuated Lysing Module

Referring to FIG. 9 a, a microfluidic device 1000 includes amicrofluidic network 1001 having a input port 1002 leading to a channel1003 including a vent 1004 and a valve 1005, which has a normally openposition but can be closed to obstruct passage of material betweenchannel 1003 and a lysing region 1006 downstream of valve 1005. Adownstream portion 1020 of lysing region 1006 joins a waste channel1008, which leads to a waste port 1009. A valve 1011 selectively allowsor obstructs passage of material along channel 1008 to waste port 1009.A gate 1022 selectively obstructs or allows passage of materialdownstream from lysing region 1006.

A thermopnuematic actuator 1014 generates a gas pressure sufficient tomove material, e.g., a lysed sample, downstream from lysing region 1006and into channel 1018. Actuator 1014 typically operates by generating anupstream pressure increase but device 1000 can be configured with anactuator that provides a downstream pressure decrease, e.g., a partialvacuum, to move material downstream from lysing region 1006. A gate 1071selectively obstructs or allows passage of material between actuator1014 and lysing chamber 1006.

Network 1001 includes a reagent input port 1032 leading to a channel1033 including a vent 1034 and a valve 1035, which has a normally openposition but can be closed to obstruct passage of material betweenchannel 1033 and a reagent metering chamber 1024 downstream of valve1035. A downstream portion 1028 of reagent metering chamber 1024 joins awaste channel 1038, which leads to a waste port 1039. A valve 1031selectively allows or obstructs passage of material along channel 1038to waste port 1039. A gate 1042 selectively obstructs or allows passageof material downstream from reagent metering chamber 1024.

A thermopnuematic actuator 1007 generates a gas pressure sufficient tomove material, e.g., an amount of reagent, downstream from reagentmetering chamber 1024 and into channel 1018. Actuator 1007 typicallyoperates by generating an upstream pressure increase but network 1001can be configured with an actuator that provides a downstream pressuredecrease, e.g., a partial vacuum, to move material downstream fromreagent metering region 1024. A gate 1073 selectively obstructs orallows passage of material between actuator 1007 and reagent meteringregion 1024.

With gates 1022, 1042 in the open state, downstream portion 1020 oflysing region 1006 and downstream portion 1028 of reagent meteringchamber 1024 lead to an intersection 1019, which is the upstreamterminus of a channel 1018. The channel 1018 leads to a reaction chamber1048 having an upstream terminus defined by a valve 1050 and adownstream terminus defined by a valve 1052. Valves 1050, 1052 can beclosed to prevent material from exiting reaction chamber 1048. A vent1054 allows degassing, debubbling of material passing along channel 1018into chamber 1048. A vent 1055 prevents pressure buildup from preventingmaterial from entering chamber 1048.

Gates and valves of network 1001 are typically thermally actuated andmay have features of other valves and gates discussed herein. Forexample, valve 1011 includes a mass of TRS 1059 and a pressure chamber1057. Increasing a temperature of TRS 1059 and a pressure within chamber1057 drives TRS 1059 into channel thereby obstructing the channel. Gate1022 includes a mass of TRS 1061 that obstructs passage of material fromlysing region 1006 to intersection 1019. Raising a temperature of TRS1061 allows upstream pressure (or a downstream partial vacuum) to movematerial from lysing region into intersection 1019 and channel 1018.

Vents of network 1001 typically include a porous hydrophobic membrane asdiscussed for vents of other devices herein. The vents allow gas toescape network 1001 but inhibit or prevent liquid from escaping.

Device 1000 is typically configured to receive a cell-containing sample,lyse the cells to release intracellular material, combine theintracellular material with reagents, e.g., reagents suitable for PCRamplification and detection, deliver the combined reagents andintracellular material to the reaction chamber 1048, amplify DNA presentin the intracellular material, and detect the presence or absence of aparticular type of cell, e.g., group B strept, based upon the detectedDNA.

Referring to FIGS. 9 b and 9 c, exemplary operation of device 1000includes introducing a volume of particle-containing sample into network1001 via inlet 1002. Sample material moves along a channel 1003 towardlysing chamber 1006. Gas, such as air bubbles possibly introduced withthe sample, are vented from the microfluidic network at vent 1004.Sample material enters and fills lysing chamber 1006. Gate 1022 isclosed thereby preventing passage of sample downstream towardintersection 1019. Excess sample material travels along waste channel1008 to a waste port 1009, which may provide passage to a waste chamber.

Even if excess sample is introduced, the volume remaining within themicrofluidic network and the position occupied by the remaining volumeis preferably determined by the volume of the respective channels andthe position of any vents (FIG. 9 b). For example, upon introduction ofthe sample, the vent 1004 prevents an upstream portion of the samplematerial from being positioned downstream of an upstream opening 1012 oflysing chamber 1006. Thus, lysing chamber 1006 is completely filled withsample material (FIG. 9 b).

Reagent materials may be introduced to network 1001 via port 1032. Wastechannel 1038 and waste port 1039 cooperate with reagent metering region1024 to deliver an amount of reagent materials and position the reagentmaterials in the same way that waste channel 1008 and waste port 1009cooperate with lysing chamber 1006 to deliver an amount of sample andposition the sample. Reagent materials may also be stored on the deviceduring manufacture as discussed elsewhere herein.

Within the sample introduced and present within lysing chamber 1006,valves 1011, 1005 are closed. Closure of valves 1011, 1005 isolatessample within lysing chamber 1006 from the atmosphere surrounding device1000. By isolate, it is meant that sample material present within lysingchamber 1006 may be heated by an amount sufficient to lyse cells thereinwithin without significant evaporation of liquid accompanying the cells.In one embodiment, for example, material within lysing chamber 1006 maybe heated to as much as 93° C., 95° C., or 97° C., for as long as 1minute, 2 minutes, 3 minutes, or even 5 minutes without substantial lossof the liquid within the lysing chamber. In some embodiments, less than20%, less than 10%, less than 5%, or less than 2.5% of the liquidpresent in the lysing chamber is lost. In some embodiments, lysingchamber 1006, like lysing chambers of other lysing modules disclosedherein, has a volume of less than 5 microliters, less than 1 microliter,less than 500 nl, less than 200 nl, less than 100 nl, less than 50 nl,e.g., less than 10 nl.

As discussed above, valves 1011, 1005 typically include a mass of TRS,e.g., wax such as parafin, that operates to obstruct or allow passage ofmaterial. In the closed state, it is the TRS that obstructs gas andheated liquid from exiting lysing chamber 1006 (or reaction chamber 1048for valves 1050, 1052). In some embodiments, the obstructing mass of TRScan have a volume of 250 nl or less, 125 nl or less, 75 nl or less, 50nl or less, 25, nl or less, 10 nl or less, 2.5 nl or less, 1 nl or less,e.g., 750 pico liters or less. Some or all of the TRS can passdownstream as discussed above.

Sample in lysing chamber 1006 is locally heated for a specified amountof time at a specific temperature to break open the target cells torelease intracellular contents which include genetic material such asDNA. Heating lysing chamber 1006 is typically localized to preventperturbation of other components of device 1000. For example, if gates1071, 1073 are thermally actuated gates, heat used to lyse cells withinlysing chamber 1006 generally does not cause premature opening of thesegates (or other gates of the device).

Turning to FIG. 9 c, upon lysing cells of sample within chamber 1006,gates 1071, 1073, 1022, 1042 are opened. An open state of gate 1071provides communication between actuator 1014 and an upstream portion oflysing chamber 1006 adjacent upstream opening 1012. An open state ofgate 1022 provides communication between sample present within lysingchamber 1006 and downstream portions of the microfluidic network. Anopen state of gate 1073 provides communication between actuator 1007 andan upstream portion of reagent metering region 1024. An open state ofgate 1042 provides communication between reagent present within meteringregion 1024 and downstream portions of the microfluidic network.

Pressure source 1022 in actuator 1014 is activated causing a pressuredifference between the upstream and downstream portions of samplepresent within lysing chamber 1006. Typically, an upstream pressureincreases relative to a downstream pressure, causing an amount of thesample to move downstream, for example to a downstream channel 1018(FIG. 16 e). Actuator 1007 is activated causing a pressure differencebetween the upstream and downstream portions of reagent within region1024. Typically, an upstream pressure increases relative to a downstreampressure, causing an amount of the sample to move downstream, forexample to a downstream channel 1018, where the reagent mixes with thelysed contents of the sample.

The volume of sample moved downstream from the lysing chamber 1006 istypically known. In the embodiment shown, for example, the volume isdetermined by the volume of lysing chamber 1006 between upstream anddownstream portions 1012, 1020 thereof. Valves 1057, 1005 may cooperatein preparation of a known amount of sample by closing alternativepassages into which material present in lysing chamber 1006 might flowupon actuation of actuator 1014.

Referring back to FIG. 9 a, device 1000 combines a known amount ofreagent with sample material, preferably with sample 1016 includingreleased cellular contents. The volume of reagent combined with thesample is determined by a volume of network 1001 intermediate an outlet1075 of actuator 1007 and gate 1042. Sample and reagent material movealong channel 1018 into reaction chamber 1048. Once reagents and samplematerial are present within chamber 1048, valves 1050, 1052 are closed.The sample reagent mixture within chamber 1048 is typically subjected toone or more heating and cooling steps, such as to amplifypolynucleotides present in the sample reagent mixture.

Thermal energy may be provided to the mixture by heating elementsintegral with device 1000 and/or by heating elements separate fromdevice 1000. For example, external heating elements may be associatedwith an operating station adapted to receive device 1000. When thedevice 1000 is received by the operating station, the heating elementsare positioned to heat particular areas, for example, actuators, valves,gates, lysing chamber 1006, and reaction chamber 1048.

In the closed state, valves 1050, 1052 limit or prevent evaporation ofthe sample reagent mixture during reaction, for example, by isolatingthe sample reagent mixture from the surrounding atmosphere. In someembodiments, the sample reagent mixture may be heated to between about90° C. and about 99.75° C., for example between about 92° C. and about98° C., for example about 97° C., for at least about 2 minutes, forexample between about 3 minutes and about 10 minutes with a loss of nomore than about 10 percent by weight, for example, no more than about 5percent, or no more than about 2.5 percent of the sample reagentmixture.

Device 1000 is typically a multilayer construction. In one embodiment,device 1000 includes a first, injection molded layer defining featuressuch as channels, chambers, valves and gates of network 1001. A secondlayer, typically a flexible laminate, overlies the first layer to sealthe network. In general, the flexible laminate has a thickness of lessthan 500 microns, such as less than 250 microns. The laminate alsoprovides efficient transfer of thermal energy between heat sourcesadjacent an outer surface of the laminate and material present withinthe microfluidic network 1001.

In some embodiments, heat sources, e.g., resistive heaters, are locatedexternal to device 1000 but in thermal communication with the outersurface of the second layer. In another embodiment, heat sources areintegrally formed with device 1000, for example, within the first,injection molded layer. Exemplary placement and operation of heatsources is discussed below and elsewhere herein.

Device 1000 may also include a third layer, which is preferably disposedadjacent a surface of the first layer that abuts the second layer. Thus,the second and third layers may sandwich the first layer therebetween.The third layer may contact a surface of the first layer that includesonly a subset, if any, of the components of the microfluidic network1001. In some embodiments, however, access ports and vents providepassage between the microfluidic network 1001 and the opposed surface ofthe first layer. For example, access ports 1002, 1032 may be configuredto allow sample material to be introduced through the third layer andinto the microfluidic network. The ports can be configured to mate witha sample introduction device, such as a syringe.

Waste ports 1009, 1039 can extend through the first and third layers toa reservoir into which excess sample and reagents introduced to themicrofluidic network may be received and contained from spillage.

Vents 1004, 1034 and other vents of device 1000 can extend through thefirst and third layers. Typically, the vents include a hydrophobicfilter that allows passage of gases but inhibits passage of cells oraqueous liquids.

Network 1001 can also include hydrophobic patches, such as a coatingwithin a portion of the microfluidic network, to assist in defining apredetermined volume of materials and positioning the materials relativeto components of the microfluidic network as discussed elsewhere herein.

Valves and Gates for Fluid Control

As discussed elsewhere herein, microfluidic devices include gates andvalves to selectively obstruct or allow passage of material withinmicrofluidic networks. For example, gates and/or valves can prevent theevaporation of liquid from a sample subjected to heating such as forlysing cells or amplifying DNA. As discussed herein, gates typicallyinclude a mass of TRS, which, in the closed state, obstructs passage ofmaterial along a channel. Upon opening the gate, at least a portion ofthe TRS typically enters a downstream channel of the device. Valvestypically operate by introducing a mass of TRS into an open channel toobstruct the channel. An exemplary device for use as a fluid controlelement, e.g., a gate or valve, is discussed below.

Referring to FIGS. 10-12, a device 500 selectively obstructs or allowspassage between an upstream portion 504 and a downstream portion 506 ofa channel 502 of a microfluidic device. For clarity, other components ofthe microfluidic device are not illustrated in FIGS. 10-12.

Device 500 can be operated as a normally closed device, e.g., a gate,which opens upon actuation to allow passage between upstream anddownstream portions 504, 506. Device 500 can also be operated as anormally open device, e.g., a valve, which closes upon actuation toobstruct passage between upstream and downstream portions 504, 506.Thus, device 500 combines features of both gates and valves, asdiscussed herein, and may be used in the place of any gate or valve ofany device disclosed herein.

Device 500 is typically implemented as a component of a microfluidicnetwork fabricated within a substrate 519 having a first layer, 520, asecond layer 522, and a third layer 524. The microfluidic network issubstantially defined between first and second layers 520, 522. In use,device 500 is located in thermal contact with a heat source, which istypically fabricated on or within a substrate 531. Substrate 531 may ormay not be integral with the substrate 519.

Device 500 includes a side channel 508, which intersects channel 502 ata gate region 507 (within box 511) thereof, and a mass of TRS 510present in at least side channel 508. When TRS 510 extends into gateregion 507, channel 502 is obstructed. When TRS does not fill gateregion 507, passage between upstream and downstream portions 504, 506 ofchannel 502 is allowed. In the closed state, a length of TRS 510 alongchannel 502 is at least about 1.5 times greater, e.g., at least about 2times greater than a width of channel 502.

Channel 502 is preferably from about 25 to about 400 microns wide andfrom about 10 to about 300 microns deep. Channel 502 has a depth that istypically from about 2 to 3 times a depth of the gate region 507, whichmay be, e.g., about 5 to about 200 microns deep. Side channel 508 may befrom about 0.75 to about 4 millimeters long and have a width of fromabout 50 to about 400 microns.

Side channel 508 includes an end 518 that connects to a hole 516 thatconnects in turn to a chamber 514. Hole 516 is at least about 100microns, at least about 150 microns, e.g., at least about 400 microns indiameter where it joins chamber 514, which may be at least about 750microns, at least about 1000 microns, e.g., at least about 1,400 micronsin diameter and at least about 150 microns, at least about 250 microns,e.g., at least about 350 microns deep. Chamber 514 and hole 516 may havenon-circular shapes. An end of side channel 508 at hole 516 can berounded with a radius of about 10 microns to about 200 microns, e.g.,about 150 microns.

Chamber 514 and channels 502, 508 are typically located on oppositesides of layer 522, which allows for a greater density of channels. Forexample, side channel 508 and channel 502 are typically defined betweenlayers 522 and 520 whereas chamber 514 is typically defined betweenlayers 522 and 524. A surface of layer 524 may define a wall of chamber514 that is larger than a surface of chamber 514 defined by layer 520. Asurface of layer 520 may define at least one wall of channel 502 andside channel 508. Typically, a surface of layer 524 does not define awall of channel 508.

Referring also to FIG. 12, device 500 includes first and second heatsources 530, 532. First heat source 530 raises a temperature of materialpresent within chamber 514 and hole 516 and at least a portion of sidechannel 508. For example, heat source 530 may heat material present inchamber 514 by an amount sufficient to raise a pressure within chamber514 by at least about 10%, at least about 20%, at least about 35%, e.g.,at least about 50%. Heat source 530 also raises a temperature of TRSpresent within hole 516 and at least a portion of side channel 508 tothe second temperature at which the TRS is more mobile. Second heatsource 532 is configured to raise a temperature of TRS present withingate region 507 to the second, temperature. The increased pressurewithin chamber 514 may move the entire mass 510 of TRS toward channel502.

In some embodiments, however, device 500 includes a single source ofheat that both raises a pressure within chamber 514 and raises thetemperature of TRS 510. Using a single heat source reduces the number ofelectrical connections required to operate device 500.

Typically, channels 502, 508, hole 516, and chamber 514 are fabricatedby injection molding layer 522. Layers 520 and 522 are typically matedto layer 522 by lamination. Layer 524 typically covers the entire openportion of chamber 514 and is preferably sufficiently rigid (or isprovided with additional support elements) to withstand flexing duringpressurization of chamber 514.

In a typical fabrication method, layer 522 is fabricated with amicrofluidic network including channel 502, side channel 508, hole 516,and chamber 514. Layers 520 and 522 are mated. With the application ofheat, TRS is loaded through hole 516. Capillary action draws the TRSinto gate region 507 thereby obstructing channel 502. Layer 524 is matedto layer 522.

Device 500 may be opened by actuating heater 532 and applying pressurewithin channel 502 to move TRS present in the gate region. Device 500may be closed again by actuating heater 530 to pressurize chamber 514and heat TRS 510 present in hole 516 and side channel 508 to the secondmore mobile temperature. The pressure within chamber 514 moves TRS 510into gate region 507. Heater 532 may also be actuated to close device500.

Microfluidic Device Configured for Mechanically-Generated Vacuum SampleIntroduction

Typical methods for introducing sample to microfluidic devices involveuser interaction with five separate objects. For example, using a tubeof transfer buffer, a syringe, a needle or non-piercing needlesubstitute, a sample-laden swab, and a microfluidic device, the usermight elute the sample off of the swab and into the tube of transferbuffer. After elution, the sample-laden buffer is drawn into the syringethrough the needle, the needle is removed, and the contents of thesyringe are injected onto the microfluidic device, such as through aninput port thereof.

Referring to FIG. 13, a microfluidic device 400 reduces the number ofobjects that must be manipulated to prepare and load a sample. Device400 includes a microfluidic network 401, a mechanical vacuum generator404, and a buffer reservoir 406. Network 401 can be defined withinlayers of a substrate and include various modules, chambers, channels,and components, as discussed elsewhere herein.

Buffer reservoir 406 is typically pre-loaded with buffer by themanufacturer but can be loaded with buffer by the user. When pre-loaded,reservoir 406 is sealed to prevent evaporation of preloaded buffer andor leakage of the buffer into network 401. For example, a cap 416 sealsbuffer reservoir 406. In use, a user deposits a portion of a sample swabinto reservoir 406. For example, a user might break off the tip of asample swab within the reservoir. Cap 416 is secured to seal the bufferand swab within reservoir 406. Thus, the user may agitate the entiredevice 400 without leakage.

Microfluidic network 401 may include any combination of features ofmicrofluidic networks 51, 110, 201, and 701 discussed above. Bufferreservoir 406 communicates with network 401 via a channel 403, which mayinclude a filter 405 configured to retain larger undesired particles,and a vent 407 configured to allow gas to escape from channel 403.

Vacuum generator 404 includes a chamber 408 defined between first andsecond gaskets 412, 413 of a plunger 410. Chamber 408 is incommunication with network 401 via a channel 414. Plunger 410 and gasket412 slide within substrate 409 expanding the size of chamber 408 betweena surface 417 of gasket 412 and gasket 413. Plunger 410 and gasket 412typically slide along a plunger axis, which is substantially parallel toa plane of network 401 and substrate 409. Vacuum generator 404 thusgenerates a reduced pressure within chamber 408 to manipulate material,e.g., sample material and/or reagent material, therein. In a preferredembodiment, the reduced pressure assists the introduction of samplematerial to device 400. In another embodiment, the reduced pressureassists the preparation of an enriched sample.

As plunger 410 is depressed (moved further into substrate 409), the sizeof chamber 408 increases. Preferably, channel 414 provides the onlypassage for gas to enter chamber 408. Thus, depressing plunger 410creates a pressure differential between chamber 408 and network 401urging material downstream within network 401 and toward chamber 408.The actuation of plunger 410 to create the at least partial vacuumtypically decreases a dimension d, of device 400. Chamber 408 andgaskets 412, 413 typically prevent leakage of material that might bedrawn into chamber 408.

Device 400 may be operated as follows. A user obtains a swab includingsample material, e.g., cells or other particulates. The swab iscontacted with buffer present in buffer reservoir 406, such as byagitating the swab within the reservoir. Cap 416 is then be secured.Plunger 410 is depressed thereby expanding the volume of chamber 404 anddecreasing the pressure therein. Plunger 410 is actuated by the user,upon placing device 400 into an instrument configured to operate device400, or by a device configured to operate device 400.

The decreased pressure (partial vacuum) resulting from plunger 410actuation draws material from buffer reservoir 406 further intomicrofluidic network. For example, sample/buffer material may be drawnpast vent 407 and through filter 405. In one embodiment, network 401includes an enrichment region as described for networks 51 and 201 andthe actuation of plunger 410 draws sample into or out of the enrichmentregion.

Device 400 may also include a mechanical seal (not shown) that isruptured or otherwise opened before or upon actuation of the mechanicalvacuum generator 404. Rupture of the seal typically releases reagents,whether dried, liquid or both, that can mix with sample introduced tothe device. In some embodiments, device 400 includes a hydrophobicmembrane (not shown) having a bubble point attained by actuation of themechanical vacuum generator. In this case, downstream components ofnetwork 401 may be sealed from the surrounding environment to preventevaporation through the membrane.

Microfluidic Device Fabrication

Typical microfluidic devices include at least first and secondsubstrates. In general, a first one of the substrates includes aninjection molded polymer having a first surface that defines channels,chambers, valves, gates and other structures of a microfluidic network.The first substrate is typically rigid enough to allow the device to bemanipulated by hand. The second substrate is generally a flexiblelaminate that overlies the first surface of the first surface and sealsthe microfluidic network. In some embodiments, a third substrate, e.g.,a second flexible laminate, overlies the second surface of the firstsubstrate. Passages defining ports and vents extend through the firstand third substrate to allow fluid to be input and withdrawn from themicrofluidic network and to allow gas and bubbles to vent from thenetwork.

An exemplary method for fabricated microfluidic devices includes (a)providing a first substrate, (b) fabricating components, e.g., channels,chambers, and gas chambers, of a microfluidic network in a surface ofthe first substrate and (c) mating a second substrate with the firstsubstrate, which preferably completes and seals the microfluidic networkwith the exception of vents, input ports, output ports and othercomponents desired that may be in communication with the environmentsurrounding the microfluidic network.

Steps may be combined. For example, an injection molding step may bothprovide a substrate while also fabricating various components of amicrofluidic network.

A preferred method for mating substrates includes lamination. The firstsubstrate is cleaned, such as with a surfactant and water and thendried. The surface to be mated with the second substrate can besubjected to a corona discharge treatment to increase the surface energyof the first surface. A standard coronal discharge gun may be used.

The second substrate is mated with the first surface of the firstsubstrate. The second substrate is preferably a flexible polymer, suchas a polymeric laminate, e.g., a high clarity LDPE tape available fromAmerican Biltrite, Inc. A layer of adhesive, e.g., a pressure sensitiveadhesive of the laminate, is generally placed between the first surfaceof the first surface and the second substrate. The mated first andsecond substrates are secured by the application of pressure and heatsuch as by using a laminator, e.g., a ModuLam 130 laminator availablefrom Think & Tinker, LTD. A typical lamination temperature is about 110°C. at of maximum velocity for the ModuLam 130 laminator.

Returning to FIGS. 4 and 5 as an example, device 200 includes a layer251 of polymer substrate, e.g., a cyclic olefin polymer such as TiconaTopas 5013. Channels and other features of network 201 are fabricated byinjection molding of the polymer substrate. The channels and otherfeatures are covered using a polymer layer 253, e.g., ABI Prismwell-plate tape. Typically, polymer layer 253 is disposed beneath layer251.

TRS of valves and gates is loaded. Retention member 94 and vent 206 arepositioned. Pitting 232, reservoir 234, and retention member support 236are positioned as part of a layer 255, which may be secured, e.g., usingadhesive sealed or heat staking, to an upper surface of layer 251. Thetop of reservoir 234 is sealed using a hydrophobic membrane (not shown)similar to that used for vent 206. Exemplary methods for mating layersof microfluidic devices of the invention are discussed below.Microfluidic devices of the present invention are preferably at leastsubstantially planar. Microfluidic networks of the present invention mayinclude a plurality of features that define at least one plane.

Microfluidic devices in accordance with the present invention generallyinclude at least a first substrate defining, on at least a first surfacethereof, elements of a microfluidic network and a second substrate,mated with the first surface of the first surface to seal at least someportions of the microfluidic network. The first substrate can alsoinclude, on a second side thereof, elements of the microfluidic network.Where the second side of the first substrate contains elements of themicrofluidic network, a third substrate can be mated thereto to seal atleast some portions of the network. Elements of the microfluidic networkcan include channels, actuators, pressure chambers, reaction chambers,detection chambers, enrichment zones, access ports, waste reservoirs andthe like.

Substrates defining elements of microfluidic networks can be formed ofany suitable material, such as silicon, quartz, glass, and polymericmaterials, e.g., a cyclic olefin. The substrate can be homogenous orformed of one or more elements bonded together, such as a siliconsubstrate having a substrate bonded thereto, e.g., a quartz cover. Atleast one of the substrate and cover are micromachined with systemfeatures, including the valves, passages, channels, and heaters.Micromachining includes fabrication techniques, such as photolithographyfollowed by chemical etching, laser ablation, direct imprinting, stereolithography, and injection molding. A preferred fabrication techniqueincludes injection molding a substrate using a machined master. Surfacesof channels and other injection-molded features may be tapered for easeof molding.

A preferred method for mating substrates includes lamination. Thelamination process can include providing a first substrate includingelements of a microfluidic network. The first substrate is preferably apolymeric substrate formed by injection molding. The first substrate iscleaned, such as with a surfactant and water. The first substrate isdried and the surface to be mated with the second substrate is subjectedto a corona discharge treatment, such as to increase the surface energyof the first surface. A standard coronal discharge gun may be used.

The second substrate is mated with the first surface of the firstsubstrate. The second substrate is preferably a flexible polymer, suchas a polymeric laminate, e.g., a high clarity LDPE tape available fromAmerican Biltrite, Inc. A layer of adhesive is preferably positionedbetween the first surface of the first surface and the second substrate.For example, the surface of the second substrate to be mated with thefirst substrate can include a layer of pressure sensitive adhesive. Themated first and second substrates are secured preferably by theapplication of pressure and heat such as by using a laminator, e.g., aModuLam 130 laminator available from Think & Tinker, LID. A typicallamination temperature is about 110° C. at of maximum velocity for theModuLam 130 laminator.

In some embodiments, the microfluidic device can include a thirdsubstrate mated with a second surface of the first substrate, the secondsurface opposing the first surface of the first substrate. The thirdsubstrate can include three dimensional features such as wastereservoirs, access ports, and the like. The third substrate and thefirst substrate can be mated using adhesive, adhesive laminate, heatstaking, and the like.

EXAMPLES Example 1 Bench Top Thermal Lysis

Two microliters of GBS culture at concentrations of about 100 cells/μlwere lysed in the capillary tubes of a LightCycler at 97° C. for 0, 1,2, 3, 4 and 5 min. After lysis, PCR (final volume: 7 μl) was performedin the same capillary tubes with GBS specific primers and probes.Purified genomic DNA from a commercial kit having from 10 to 10,000copies was used to prepare standards for quantification. Theamplification results indicate that as little as 1 min was sufficient tolyse the GBS cells.

Example 2 Lysis on Microfluidic Device

A microfluidic device including an epoxy-based substrate defining a 500nl lysing chamber covered by a glass coverslip was prepared. About 500nl of the GBS of Example 1 was loaded into the lysing chamber. The inputport was sealed with an adhesive polymer. The chip was placed on aheater and lysed at 97° C. for 2 min. The sample was retrieved bypipette and the volume of sample were brought up to 10 μl with TE buffer(pH 8.0). About 2 μl of this diluted sample was subjected to PCR. Theexperiment was repeated several times. The PCR amplification resultsdemonstrate that a time of 2 min was sufficient to lyse the cells.

Injection molded microfluidic devices each having a lysis channel wereprepared. The devices included two tapered holes at each end of a lysischannel, thereby allowing easy loading and retrieval of samples. Thelysis channel was sealed with a laminate allowing efficient heatconduction and increasing the speed of device assembly.

Cultured GBS cells were diluted to a concentration of about 5,000 cellsper μl in TE buffer and loaded into the lysis chambers of the devices.The lysis chambers had a volume of about 1 μl. The devices were heatedto 97° C. for 0, 0.5, 1, 2, or 3 minutes. PCR amplification resultsindicated that lysis was essentially complete within 1 minute.

Example 3 Clinical Testing

Approximately 2 ml of GBS swab samples were submitted to themicrobiology of a University Hospital for culturing. Samples of GBShaving a volume of about 0.5 ml were prepared and stored at 4° C. forless than 24 hours. A code was assigned to each sample so the identityof the individual could not be determined. Samples were spun down in acentrifuge at 14 kRPM for about 2 min and resuspended in 0.5 ml TE with0.02% SDS. The samples were then passed through a 3 μm Versapor Acrodiscsyringe filter (Pall Gelman Laboratory) and spun down again. Aftercentrifugation, the cells were resuspended in 1 μl of 0.02% SDS in TEbuffer. The entire sample was loaded into a lysis chamber of amicrofluidic device and sealed with laminate. The devices were heated to97° C. for 3 min to lyse the cells. Samples were retrieved with apipette and the volume of the samples was brought up to 5 μl. A 1 μlaliquot of the diluted samples was used for PCR with GBS specificprimers and a GBS specific Taqman probe in a LightCycler. The clinicalsensitivity: 83%; clinical specificity 91%, positive predictive value65% and negative predictive value: 96%.

GBS samples as described above were combined with about 1 ml ofTriton-X-1000 buffer and filtered through a polycarbonate filter(Poretics). The samples were lysed at 97° C. for 3 min to lyse thecells. The clinical sensitivity was 91%. The clinical specificity was91%. The positive predictive value was 69% and the negative predictivevalue was 98%.

While the above invention has been described with reference to certainpreferred embodiments, it should be kept in mind that the scope of thepresent invention is not limited to these. Thus, one skilled in the artmay find variations of these preferred embodiments which, nevertheless,fall within the spirit of the present invention, whose scope is definedby the claims set forth below.

1-6. (canceled)
 7. A microfluidic valve contained in a microfluidiccartridge to selectively obstruct passage of material in a microfluidicnetwork of the microfluidic cartridge, the valve comprising: a sidechannel in communication with a main channel of the microfluidicnetwork, the side channel and the main channel being located in a commonplane of the microfluidic cartridge; a chamber in communication with theside channel and being located vertically above the side channel; and athermally responsive substance disposed within the side channel.
 8. Themicrofluidic valve of claim 7, wherein the side channel and main channelare in communication at a proximal end of the side channel.
 9. Themicrofluidic valve of claim 7, wherein the side channel and the chamberare in communication at a distal end of the side channel.
 10. Themicrofluidic valve of claim 7, wherein the chamber is in thermalcommunication with a heat source.
 11. The microfluidic valve of claim10, wherein the heat source is in a substrate separate from themicrofluidic cartridge.
 12. The microfluidic valve of claim 7, whereinthe side channel is in thermal communication with a heat source.
 13. Themicrofluidic valve of claim 12, wherein the heat source is in asubstrate separate from the microfluidic cartridge.
 14. The microfluidicvalve of claim 7, wherein a top portion of the chamber has a largerdiameter than a lower portion of the chamber.
 15. The microfluidic valveof claim 7, wherein the chamber comprises a frusto-conical verticalprofile.
 16. The microfluidic valve of claim 7, wherein the valve is inan initially open state when the thermally responsive substance isdisposed within the side channel, such that the material is allowedpassage through the main channel of the microfluidic network past themicrofluidic valve.
 17. The microfluidic valve of claim 7, wherein thevalve is in a closed state when at least a portion of the thermallyresponsive substance moves from the side channel to the main channel,thereby obstructing passage of material in a microfluidic network pastthe microfluidic valve.
 18. A microfluidic valve contained in amicrofluidic cartridge to selectively obstruct passage of material in amicrofluidic network of the microfluidic cartridge, the valvecomprising: a first layer; a second layer, the first and second layerdefining a side channel therebetween, the side channel being incommunication with a main channel of the microfluidic network; a thirdlayer, the second and third layer defining a chamber therebetween, thechamber being in communication with the side channel; and a thermallyresponsive substance disposed within the side channel.
 19. Themicrofluidic valve of claim 18, wherein the side channel and the mainchannel are in the same plane of the microfluidic network and thechamber is located vertically above the side channel.
 20. Themicrofluidic valve of claim 18, wherein the chamber is in thermalcommunication with a heat source.
 21. The microfluidic valve of claim20, wherein the heat source is in a substrate separate from themicrofluidic cartridge.
 22. The microfluidic valve of claim 18, whereinthe side channel is in thermal communication with a heat source.
 23. Themicrofluidic valve of claim 22, wherein the heat source is in asubstrate separate from the microfluidic cartridge.
 24. The microfluidicvalve of claim 18, wherein the chamber is at least about 150 μm deep.25. The microfluidic valve of claim 18, wherein the side channel isbetween about 50 μm and 400 μm wide.
 26. The microfluidic valve of claim18, wherein the side channel is between about 0.75 mm and 4 mm long.